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Keywords:

  • circular dichroism spectroscopy;
  • dynamic light scattering;
  • enamel matrix protein;
  • intrinsically disordered proteins;
  • protein structure

Wald T, Bednárová L, Osička R, Pachl P, Šulc M, Lyngstadaas SP, Slaby I, Vondrášek J. Biophysical characterization of recombinant human ameloblastin. Eur J Oral Sci 2011; 119 (Suppl. 1): 261–269. © 2011 Eur J Oral Sci

Ameloblastin (AMBN) is a protein expressed mainly during dental hard tissue development. Biochemically, it is classified as an intrinsically disordered protein (IDP). Its biological role remains largely unknown; however, the question of AMBN function will undoubtedly be connected to its structural properties and its potential for protein–protein and protein–cell interactions. A basic biophysical characterization of human recombinant ameloblastin (hrAMBN) and its N- and C-terminal domains by means of circular dichroism spectroscopy and dynamic light scattering showed that under physiological conditions ameloblastin is an IDP with a prevalent polyproline-II (PPII) conformation. Both the N- and C-terminal polypeptides, when expressed independently, showed different structural preferences upon heating as well as different behaviour in the presence of trifluoroethanol and CaCl2 salt. The N-terminal peptide showed a more ordered structure with a strong tendency to adopt a helical conformation upon the addition of trifluorethanol, whereas the C-terminal domain seemed to be primarily responsible for the structural disorder of the entire AMBN molecule.